That picture doesnt have any detail at ALL. You are going to have to get us something way more detailed to give you an idea on when to harvest. Till then read the FAQs. Get a hand magnifier or loupe, and look for the trichomes (crystals on the buds) to turn cloudy or slightly amber (this is when to harvest). See the sticky post at the top of the basic growing forum by StinkyAttick for more info...